Emerson

Model 304

12"
Mirror in Lid. This set is similar to the RCA TRK-12. In the 1940
book Principles of Television Engineering, by Donald Fink,
there is a reference to RCA providing power supply and deflection
chassis to other manufacturers. This set, along with the Andrea 2-F-12 and 8-F-12, has these chassis.
(Thanks to Tim Mullen for this information). Here is more information.